Product applicators are designed to deliver a quantity of product. In consumer goods there are, broadly, two types of handheld applicators. There are applicators that are separable from a product container/reservoir. Throughout the specification, a “separable applicator” is one that is disconnected from a product reservoir at the time of applying product to a target surface. In use, a separable applicator is loaded with product from a product reservoir for transfer to a target surface. In contrast, there are applicators that are integral with a product container and therefore, the applicator cannot be separated from the product container. This type of device dispenses product by causing the product to flow from a reservoir, through the interior of an applicator, and out an exit structure, for transfer to a target surface. The present invention is concerned with the first type of heated applicator, that which is separable from a product container.
A heated applicator that is separable from a product container has different issues than a heated applicator that is integral with a dispensing container. In the case of a heated applicator that is separated from a product container at the time of use, the electronic circuitry may be housed solely within the applicator, and not within the container, if power is to be continuously supplied to the applicator. In contrast, in the case of an applicator that is integral with a dispensing container, the electronics is not limited to being housed within the applicator. The container portion provides substantially more space for a layout of electric circuits. In fact, dispensing containers with integral applicators and heating elements may be no larger than dispensing containers with integral applicators having no heating elements. Separable applicators are different, at least in cosmetics and personal care. Here, such applicators tend to be sleek and designed for easy storage in a small purse or pocket. In the personal care field, the drive is always to make smaller, more convenient applicators of this type. Therefore, when the addition of heating components to an applicator requires making the applicator larger, this is a clear disadvantage. This disadvantage is not as often encountered when designing dispensing containers with integral applicators, because dispensing containers with integral applicators do not have to be enlarged at all or to the same degree as separable applicators.
Mascara products are very popular. Today, mascara sales approach eight hundred million dollars per year in the United States alone. Because of this, significant resources are devoted to the development of innovative mascara products. Innovative mascara products are those that introduce new features to the consumer or that improve upon exiting mascaras by making them perform better or by making them less expensive. Innovation in mascara products may occur in the composition or in the applicator used to apply the composition. Being innovative in the field of mascara products can be a challenge because mascara compositions are one of the most difficult cosmetics to formulate, package and apply. In part, this is owing to the physical and rheological nature of the product. Mascara can be a heavy, viscous, sticky and often messy product. It does not flow easily in manufacture, filling or application, while drying out quickly at ambient conditions. It may contain volatile components that make safety in manufacture an issue. Mascara is also difficult because of the target area of application. The eyelashes offer a very small application area, while being soft, flexible, delicate and in close proximity to very sensitive eye tissue. Being flexible, the eyelashes yield easily under the pressure of a mascara applicator which makes transfer of the product onto the lashes difficult. The act of transferring a rheologically difficult product to a small, delicate target and in so doing achieve specific visual effects, is the challenging task of mascara application.
The most common mascara applicator is the mascara brush. A classic mascara brush has a bristle head that comprises a collection of individual filaments disposed within a helical wire core. The wire core depends from one end of an elongated stem, while the other end attaches to a handle. Also known, are molded bristle heads, which are fashioned as a cylindrical sleeve with integrally molded bristle elements radiating from the sleeve. The molded sleeve may be slipped over one end of an elongated stem, while the other end of the stem attaches to a handle. In either case, the radially extending bristles, collectively, form a bristle head or applicator head, the “working portion” of the applicator. For a review of those brush parameters that are recognized by a person of ordinary skill in the art to be results-effective, see U.S. Pat. No. 7,465,114, herein incorporated by reference, in its entirety.
Regarding mascara compositions, there is an established vocabulary for discussing their performance characteristics. Each of these characteristics can be evaluated and assigned a number on an arbitrary scale, from 0 to 10, say, for purposes of comparison during formulation. “Clumping”, as a result of mascara application, is the aggregation of several lashes into a thick, rough-edged shaft. Clumping reduces individual lash definition and is generally not desirable. “Curl” is the degree to which a mascara causes upward arching of the lashes relative to the untreated lashes. Curl is often desirable. “Flaking” refers to pieces of mascara coming off the lashes after defined hours of wear. The better quality mascaras do not flake. “Fullness” depends on the volume of the lashes and the space the between them, where “sparse” (or less full) means there are relatively fewer lashes and relatively larger separation between the lashes and “dense” (or more full) means the lashes are tightly packed with little measurable space between adjacent lashes. “Length” is the dimension of the lash from the free tip to its point of insertion in the skin. Increasing length is frequently a goal of mascara application. “Separation” is the non-aggregation of lashes so that each individual lash is well defined. Good separation is one of the desired effects of mascara application. “Smudging” is the propensity for mascara to smear after defined hours of wear, when contacting the skin or other surface. Smearing is facilitated by the mascara mixing with moisture and/or oil from the skin or environment. “Spiking” is the tendency for the tips of individual lashes to fuse, creating a triangular shaped cluster, usually undesirable. “Thickness” is the diameter of an individual lash, which may be altered in appearance by the application of mascara. Increasing thickness is usually a goal of mascara application. “Wear” is the visual impact of a mascara on the lashes after defined hours as compared to immediately after application. “Overall look” is one overall score that factors in all the above definitions. It is a subjective judgment comparing treated and untreated lashes or comparing the aesthetic appeal of one mascara to another. The ideal mascara will possess all of the desirable properties while avoiding the undesirable.
Often, the formulator is interested in achieving thicker, fuller, well separated lashes. Characteristics like clumping and spiking tend to work against this, and a developer can improve one or more characteristics only at the expense of others. For example, to increase the fullness of a particular mascara, conventional wisdom suggests adding more solids (wax) to the composition. However, a disadvantage of doing this is that it tends to increase clumping of the composition and decrease the user's ability to separate the lashes. A high level of solids can also create a negative sensorial effect because the high concentration of solids makes the mascara difficult to spread over the lashes. The result can be tugging on the lashes, discomfort associated therewith and a poor application. The art of conventional mascara formulation can be a balancing act between separation and volumizing, between too much of one and not enough of the other. Embodiments of the heated applicators and formulations address this difficulty. As noted, during formulation, for purposes of comparison, each of the above characteristics can be evaluated and assigned a number on an arbitrary scale. For example, if the performance scale is 0 to 10, then a substantial improvement in mascara performance may be understood as an increase of 1 or more points, in one or more characteristics, preferably with no decrease in any one characteristic.
Conventional mascara formulations include oil-in-water emulsion mascaras which may typically have an oil phase to water ratio of 1:7 to 1:3. These mascaras offer the benefits of good stability, wet application and easy removal with water, they are relatively inexpensive to make, a wide array of polymers may be used in them and they are compatible with most plastic packaging. Oil-in-water mascaras may not stand up well to exposure of water and humidity. Oil-in-water mascaras are typically comprised of emulsifiers, polymers, waxes, fillers, pigments and preservatives. Polymers behave as film formers and improve the wear of the mascara. Polymers affect the dry-time, rheology (i.e. viscosity), flexibility, flake-resistance and water-resistance or water-proofing of the mascara. Waxes also have a dramatic impact on the rheological properties of the mascara and will generally be chosen for their melt point characteristics and their viscosity. Inert fillers are sometimes used to control the viscosity of the formula and the volume and length of the lashes that may be achieved. Amongst pigments, black iron oxide is foremost in mascara formulation, while non-iron oxide pigments for achieving vibrant colors has also become important recently. Preservatives are virtually always required in saleable mascara products.
There are also water-in-oil mascaras whose principle benefit is water resistance and long wearability. These mascaras may typically have an oil phase to water ratio of 1:2 to 9:1. Water-in-oil mascaras are typically comprised of emulsifiers, solvents, polymers and pigments. Volatile solvents facilitate drying of the mascara. Polymers play a similar role in water-in-oil mascaras as in oil-in-water discussed above, although in the former, an oil miscible film forming polymer is recommended. The same classes of pigments may be used in water-in-oil mascaras, as in oil-in-water. Here though, a hydrophobically treated pigment may provide improved stability and compatibility.
U.S. Pat. No. 7,083,347, U.S. Pat. No. 7,090,420, US 2005/0031656 and US2005/0013838 (herein incorporated by reference, in their entirety) disclose a combination of mascara and heating applicator. More specifically, these references describe the use of heating applicators with mascaras that have certain thermal behavior and melting characteristics, when measured according to the patentee's disclosed test methods. For example, the thermal behavior and melting characteristics are measured with the aid of a differential scanning calorimeter.
Due to the various materials found in commercial mascara, a mascara composition displays an initial melting point (defined as the temperature at which 5% of the enthalpy of melting is consumed), an end melting point (defined as the temperature at which 95% of the enthalpy of melting is consumed). These references define formulations according to their temperature amplitude (i.e. final melt temperature minus initial melt temperature). In a DSC plot of heat flow (absorbed power) versus temperature, the initial and final melting points may be observed, as well as one or more peaks. The compositions described in these references are those that exhibit a melting-peak width at mid-height, of less than or equal to 20° C. or 10° C. Furthermore, the '347, '420, '656 and '838 references also disclose that the heating applicator is able to raise the temperature of the formulation above the formulation's melting point (defined as the temperature corresponding to the apex of the peak in the DSC curve).
Furthermore, a careful reading shows that the '347, '420, '656 and '838 references are concerned with “thermally stable” compositions. As that term is defined therein, and adopted here, a “thermally stable” formulation is defined as one whose viscosity varies by no more than 25%, after being subjected to a succession of no fewer than 4 melting/cooling cycles according to the following protocol. The formulation is placed in a temperature chamber at 80° C. for 2 hours. The formulation is then left to return naturally to ambient temperature. Its viscosity is measured after completing at least 4 cycles. A period of 24 hours is left between two successive cycles. The viscosity measured after completing at least 4 melting/cooling cycles, is compared with that measured before the first cycle.
It is known for heated cosmetic and personal care applicators utilize conventional, flexible metallic wiring and contacts for conducting electricity from a power source to a switch, then to a heating element and possibly to one or more light indicators and temperature controls, before returning to the power source. If more than one independent circuit is required, then the number of wires and electrical connections increases proportionately. In contrast, heated applicators according to embodiments of the present invention do not use metal wire conductors or use substantially fewer, do not have the space constraints associated with using wire circuitry, substantially reduce the labor required to assemble an applicator, have more reliable electrical connections and sophisticated electrical options, and reduced circuit length.